1 #include <sys/ioctl.h>
2 #include <sys/types.h>
3 #include <sys/stat.h>
4 #include <fcntl.h>
5 #include <stdio.h>
6 #include <errno.h>
7 #include <string.h>
8 #include <inttypes.h>
9 #include <unistd.h>
10
11 #include <linux/usbdevice_fs.h>
12
13 /* For building without an updated set of headers */
14 #ifndef USBDEVFS_DROP_PRIVILEGES
15 #define USBDEVFS_DROP_PRIVILEGES _IOW('U', 30, __u32)
16 #define USBDEVFS_CAP_DROP_PRIVILEGES 0x40
17 #endif
18
19 void drop_privileges(int fd, uint32_t mask)
20 {
21 int res;
22
23 res = ioctl(fd, USBDEVFS_DROP_PRIVILEGES, &mask);
24 if (res)
25 printf("ERROR: USBDEVFS_DROP_PRIVILEGES returned %d\n", res);
26 else
27 printf("OK: privileges dropped!\n");
28 }
29
30 void reset_device(int fd)
31 {
32 int res;
33
34 res = ioctl(fd, USBDEVFS_RESET);
35 if (!res)
36 printf("OK: USBDEVFS_RESET succeeded\n");
37 else
38 printf("ERROR: reset failed! (%d - %s)\n",
39 -res, strerror(-res));
40 }
41
42 void claim_some_intf(int fd)
43 {
44 int i, res;
45
46 for (i = 0; i < 4; i++) {
47 res = ioctl(fd, USBDEVFS_CLAIMINTERFACE, &i);
48 if (!res)
49 printf("OK: claimed if %d\n", i);
50 else
51 printf("ERROR claiming if %d (%d - %s)\n",
52 i, -res, strerror(-res));
53 }
54 }
55
56 int main(int argc, char *argv[])
57 {
58 uint32_t mask, caps;
59 int c, fd;
60
61 fd = open(argv[1], O_RDWR);
62 if (fd < 0) {
63 printf("Failed to open file\n");
64 goto err_fd;
65 }
66
67 /*
68 * check if dropping privileges is supported,
69 * bail on systems where the capability is not present
70 */
71 ioctl(fd, USBDEVFS_GET_CAPABILITIES, &caps);
72 if (!(caps & USBDEVFS_CAP_DROP_PRIVILEGES)) {
73 printf("DROP_PRIVILEGES not supported\n");
74 goto err;
75 }
76
77 /*
78 * Drop privileges but keep the ability to claim all
79 * free interfaces (i.e., those not used by kernel drivers)
80 */
81 drop_privileges(fd, -1U);
82
83 printf("Available options:\n"
84 "[0] Exit now\n"
85 "[1] Reset device. Should fail if device is in use\n"
86 "[2] Claim 4 interfaces. Should succeed where not in use\n"
87 "[3] Narrow interface permission mask\n"
88 "Which option shall I run?: ");
89
90 while (scanf("%d", &c) == 1) {
91 switch (c) {
92 case 0:
93 goto exit;
94 case 1:
95 reset_device(fd);
96 break;
97 case 2:
98 claim_some_intf(fd);
99 break;
100 case 3:
101 printf("Insert new mask: ");
102 scanf("%x", &mask);
103 drop_privileges(fd, mask);
104 break;
105 default:
106 printf("I don't recognize that\n");
107 }
108
109 printf("Which test shall I run next?: ");
110 }
111
112 exit:
113 close(fd);
114 return 0;
115
116 err:
117 close(fd);
118 err_fd:
119 return 1;
120 }
121
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